Synchronizing apparatus



Jgly s, 1930. A, R DMS 1,769,988

SYNCHRONI Z ING APPARATUS Filed Feb. 5. 1927 7\ lNvENToR IMQIDMI #isATTORNEYS Patented July 8, 1930 PATENT OFI-Ica y .ARTHUR IP. DAVIS, FNEW YORK, N. Y.

sirNcHRoNIzINGfl APPABT'US v AApplication led February 5, 1927. SerialNo. 166,083.

This invention relates to a systemfor automatically comparing thefrequencies of sounds emitted periodically from a p1ural-.

ity of dierent sources, and more particularc 5 ly concerns ja system forcomparing frequencies of the'beats of a watch, clock or other time pieceto the frequency of the 'beats of a standard or substantially accuratetime piece of the same type. f All time pieces of a given type areusually constructed from identical parts, but-'because of slightvariations in the physical properties of the materials used, as well asvariations in assembling thesel parts, vthere is l5 frequently a markedvariation between the speed of .operation of -time pieces soconstructed.v @O

4After being assembled, time piecesl are usually compared with astandard time 'ece,

that is, one which runs accurately at standard time, andare adjusted`until they run approximately at thesame rate as does the standard timepiecefrFhis adjustment is usually accomplishedl'by observing tli/e 25movement of the hands, and this type .of

comparison must continue over an extended perlod of time 1f accurateresults are to be obtained, acomparison lasting twenty-four;-

hours 4or more being necessary to obtain an ordinary degree -ofaccuracy. In the manufacture of watches4 and certain other time pieces,it is customary to construct al]I9 of a given'type of. such instrumentsto give a predetermined number of beats per minute when adjusted tostandard time.

Thus a comparison between the rateofooperg ation of a standard watch anda watch to be adjusted may be 'obtained by comparing the frequenciesofthe beatsthereof. As most watches are'constructed to run at the rateof about three hundred beats per minute, it is obviouslyl impossible,from a practical standpoint, to accurately cmpare the beats methods. l

Withthe above and other considerations in mind, it is an'object of thepresent inven tion to 4provide asystem by means of which the beats of'aplurality of watches or other time pieces may be very quickly and acofwatchesfdirectly by ordinary physical.

curately compared and, moreo specifically it is proposed to provide astem of this nature including a device whlch directly indicates which oftwo watches is running at the higher rate, and also 'ves a direct in- 55dication of the diii'erence etween the rates of operation of the twowatches.

Itisfa further object of the present invention to rovide a s stemincluding means for ampli ying the eats of the watches being compared,so that these beats `may operate suitable indicating means. Otherspecific objects, advantages and characteristic features of the presentinvention will become apparent as the description thereof progresses. l

In describing the invention in detail, reference will be" made to theaccompanying ratus of the present invention; and

Fig. 1 is a simplified and diagrammatic showing of the frequency compangapparatus of the present invention; and

Fig. 2 is a sectional view of a modied form of means for responding tothe beats of the watches being compared.

Referring to the drawing, and more particularly to Fig. 1, the apparatusof the present invention comprises, in general, two microphones'or othersound responsive devices M and for responding to the beats of the watchs being com ared, two amplifying devices A and A or amplifying theelectrical impulses produced in the microphones, and an indicating'instrument S responsive to the output currents of-the tvgo, amplifiers,for indicating directly the differenceD in `speed of operation of thetwo watches and also indicating which of the Y two watches is operatingat the higher speed.

The sound orn vibration responsive devices M and M and the ampliiers A.and A have been sh wn `as microphones and vacuum amplifie respectivelyin the preferred embodiment of the invention illustrated. It shouldbe-elearly understood, however, that other forms of responsive devicesand other forms of amplifiers, such as. mechanical amplifiers of therelay, tuned reed or other type, might be yused without departing fromthe scope of the invention disclosed.`

The sound responsive devicesLM and M may take any one of a number'mfsuitable forms, and in the embodiment shown, comrises microphones of thewell known type 1n which the resistance of an electric circuit is varied'by'sound impulses impressed on a diaphragm. The micro hones M and M areconnected respective y to the pri'- -mary windings -2 and 2 of twotransformers T and T through circuits including the battery v3, thesecircuits being tuned. to resonance a't substantially the frequency ofthe beats of the watches by means of they condensers 4 and 4. Thecircuit for the microphone M ma be traced as follows z-from the micropone M, wires 5 and 6, primary winding 2 of transformer T, wires 7, 8, 9,and 11, battery 3, andwires 12, 13, 14,15 and 016 tothe micro hone M.The circult for the microphone follows :-from the microphone M', wires17 and 18, primary winding 2 of transformer v T', `wires-19, 20, 10 and11, battery 3.and

wires 12, 13, 14,'15`an'd 21 to the microphone M.

The` transformers T and T may take any suitable form, and are preferablyof the iron -core type, having any suitable or desi-red ratio of voltagetransformation. u The input circuits of the 'transformers T and T arerather broadly tuned by the condensers 4 and 4, so. that these circuitsare particularly sensitive to a band of frequencies representing theusual variations from standard beat frequency ordinarily encountered inwatches that have not been regulated. 'l

In the vacuum tube amplifier of the disclosed embodiment of theinvention, the secondary windings 22 and 22 of the transformers T and Tare directl connected respectively tothe input or grid-filament circuitsof two vacuum tubes V and V of the well known three element type. Thefilaments 23 and 23 of the vacuum tubes V and V are heated by'currentsfrom the battery 3 throughcircuits which are obvious from the drawing,and the plate circuits of these tubes rare connected through-a platebattery 24'to the armature and field windings respectively of theindicating instrument S as hereinafter described. The plate circuit ofthe vacuum tube V is preferably connected in series with the primarywinding of a transformer T of any suitable form, and the ield Windingsof the instrument S are connected with the secondary winding 66 of thistransformer as hereinafter described, and in this manner an alternatingcurrent is impressed on these field windings. It should be understood4that a transformer may also be included in "i the plate circuit of thetube V which supplies energy to the armature winding of the instrumentS, or the plate circuits ofboth of the tubes V and V may be connecteddirectly to may^be traced as found preferable.

The indicating instrument S may take any suitable form, but is.preferably of the form generally known as a synchroscope, that is,

an instrument having arotary armature element whichl indicates, by itsspeed of rotation, the difference in the frequency between twoalternatin or pulsating currents impressed respective y on its field'and armature windings, and also indicates, by the direction of rotationof the armature, which current has the higher frequency. In theembodiment shown, the instrument S includes a rotor or armature 25comprising a pivotally mounted shaft 26 of soft iron or other suitablemagnetic material, surrounded by a stationaryl armature coil orvwinding27, and carrying two oppositely disposed sector shaped vanes 28 and 29at the ends thereof as shown. The shaft 26 is journalled in suitablebearings carried by a frame, not shown, and a pointer 30is fixed to oneend of the shaft and arranged to move in close proximity to a stationarycircular scale 31, a section of which -has been shown in the drawing.The scale is preferably provided with graduations 32, and withoppositely directed arrows 33 and 34, the arrows being designated bysuitable distinctive indicia and acting to designate the significance ofthe direction of rotation ofthe pointer 30.

The field structure of fthe instrument S comprises a plurality of spacedfield windings, and as shown, each pair of diametrically oppositewindings 35, 36 and 37, 38 is connected in series and these two pairsarealso connected in multi le. A condenser 39 is connected in series withthe windings 37 and 38 and acts to maintain a phasedisplacement betweenthe currents fiowing in the two pairs of windings. d

The plate circuit of the vacuum tube'V is connected iu series with the.armature winding 25 through a circuit which may be traced as followsz-from plate 40 of the tube V, wire 41, armature winding 27, wires 42,67 and 68, plate battery 24 and wires 45, 13, 14 and 46 to the filament23 of the `vacuum tube V. The plate circuit of the vacuum tube V isconnected to the primary winding of the transformer T" through a circuitwhich maybe traced as follows from the plate 40( of the vacuum tube V',wire 69, primary winding 65 of transformer T", wires 70 and 68, platebattery 24 and wires 45, 13 and 54 to the filament 23 of vacuum tube V.The secondary winding 66 is connected with the field windings of theinstrument S through a circuitwhich may be traced as follows from thewinding 66, rwire 47, divided through two parallel paths, one of whichcomprises field winding 35, wire 48, field winding 36 and wires 49 and43, and the other of which comprises wire 50, condenser 39,

.wire 51,1-1e1d winding 3s, wire 52,5e1d winding 37 and wire 53, thencethrough wire 44, tof

the secondary winding 66 of the transformer T.

I n the operation of the apparatus described, two watches or other timepieces W and W are placed in close proximity in microphones M and Mrespectively, these watches being preferably supported by the mouthpieceof the microphone as shown. One of these watches, say the watch W', is astandard watch, that is, a watch which has:

M or M, the beats are transmitted to thev microphone mechanism bytheresultant mechanical vibration of the mouthpiece as well as by soundwaves, and hence appreciable variations of current are readilyobtainable in the microphone circuits. i

The current variations in the primary circuits of the transformers T andT are amplified by these transformers and by the The frequencies ofthese plate currents correspond to the beat frequencies of the watches Wand W respectively, and these plate currents are impressed respectivelyon the armature and field windings of the instrument S, the platecurrent from the tube V being converted from pulsating to alternatingcurrent in the transformer T. The alternating current in the secondarycircuit of the transformer T produces a rotating magnetic field in theinstrument S due to the phase displacement produced by the condenser 39,and, unless the frequency of the plate current from the tube V flowingin the armature winding 27 is of exactly the same frequency as the iieldcurrent, thearmature 25 will rotate Ain one direction or another, due tothe magnetic reactions between the field and the armature. The armaturerotates in one direction if the field current is of the higher frequencyand in the opposite direction if the armature current is of the higherfrequency, and in this manner the direction of rotation of the armatureand its associated pointer .30 indicates whether the watch W under testis running faster or slower than the standard .es watch lV. Also, thespeed at which the ar- `mature 25 and the pointer 30 rotate depends uponthe difference between the'eld and armature frequencies of theinstrument S and so gives an indicationof the difference in speed ofoperation of the two watches.

As soon as the two watches are placed on the microphones, the comparisonbetween their respective speeds of operation is obtained, and the watchW under test may be regulated to increase or decrease its speedaccording to. whether the instrument S has indicated that this watch isrunning faster or slower. than the standard watch W. After regulation,the watch W is again compared to the watch W as before, the speed anddirection of rotation ofthe armature 25 and its associated pointer 30directly indieatingV the accuracy with which the. watch W under test hasbeen adjusted. If the watch W has been adjusted to run at exactly thesame rate as the 'standard watch W', the armature 25 remains stationary.It is not ordinarily necessary, however, to obtain an absolutelyaccurate adjustment of the watch under test, the adjustment beingsuiicient for practical purposes if the armature 25 and the pointer 30move at a very low rate of speed. y'

Where the beat of the watch is very light,

so that very little sound is emitted thereby, 9

or where it is desired to obtain comparatively large current variationsin the microphone circuits, a modified form of microphone as shown inFig. 2 may be employed. This modified microphone includes the usualvariable resisting element 60, connected with a diaphragm 61, 'a rod 62being rigidly secured to the diaphragm 61 and the element 60, andextendingoutwardly to a point substantially in alignment with the outeredges of the mouthpiece 63. When a watch W is placed upon the mouthpieceof a diaphragm Lof this form, the rod 62 is engaged by the case of thewatch, and vibrations due to the beats of the watch are eliicientlytransmitted to the variable resistance element through this rod.

Obviously, the frequency comparing apparatus of the present inventionhas many very desirable features. By the use of this apparatus, the rateof operation of two Watches may be accurately compared` in a very short`period of time, less than a minute being consumed making such acomparison. The instrument S quickly and accurately indicates not onlythe differences in speed between the two watches, but also, which of thewatches is operating at the higher -rate of speed. Thus, in adjustingawatch, it is not necessary to employ cut and try methods, as theoperator is immediately informed as to whether the watch under test isrunning too slowly or too rapidly, and has a general indication of justhow much too slowly or rapidly such watch is running. The apparatus ofthe resent invention is very simple and rugged 1n its construction,embodying only one moving element. The operation of the apparatus of thepresent invention is also extremely simple, and does not require theservices of a skilled or specially trained operator.

Although the frequency comparing apparatus of the present invention hasbeen-described in connection with certain specific elements andcombinations, it should be clearly understood that the invention is notlimited in its' scope to the exactl details or combinations' disclosed.For example, means other than microphones'may be employed for respondingto the beats of the watches, and

other forms of amplifying means besides the vacuum tube amplifiers ihownmight be used.

The indicating instrument might take any V one of a number of suitableforms and manyother changes, modications and omissions might be madewithout departing from the scope of the invention as defined by theappended claims. n

I claim:

1. Apparatus for comparing the frequencies of periodic vibrations froma. plurality of different sources comprising means responsive to saidvibrations, and an indicating device controlledby said means fordirectly indicating which of said frequencies. is the higher and forgiving a direct indication of 4 the differencebetween said frequencies.

2. Apparatus for comparing two series lof impulses from independentsources comprising separate means responsive to the impulses fromeachsource, means-for amplifying the impulses received bysaid firstmeans from each source, anda singleindicating device, responsive to saidtwoseriesiof amplified impulses, for indicating the ""'instantaneousdifference in frequency between the two series of impulses vand forindicating which series has the higher frequency.

3. Apparatusfor comparing two separate series of impulses fromindependent sources comprising separate means, each responsive to one ofsaid series of impulses, for varying 'electric currents in accordancewith the fre- `quencles of saldimpulses, and a single electro-responsivedevice, operated by the simultaneous application of said electriccurrents thereto, for directly indicating the difierence in frequencybetween said two series of impulses and for directly indicating whichseries has the higher frequency.

4. Apparatus for comparing two separate series of impulses fromindependent sources comprislng separate means, each responsive to-.oneof said series of impulses, for varying electric currents in accordancewith the frequencles of said lmpulses, means for separately amplifyingsaid electric currents, and a'slnglc electro-responsive device operatedby the, simultaneous differential effect of said electric currentsthereto, and havinga single vmeans for separately amplifying saidelectric currents, and a single movable' element 4responsive to'said twoamplified currents for simultaneouslyindicating the difference infrequency between the vibrations from said devices and which of thevibrations has the higher frequency.

6. Apparatus for comparing the speed of operation of two mechanicaldevices comprising separate means responsive severally to periodicvibrations of said devices, said means varying electric currents inaccordance with the frequencies of said vibrations, two audion tubeamplifiers for separateqy amplifying said currents, and a single movableelementv responsive to said two amplified currents for simultaneouslyindicating the difference in frequency between the pediodic vibrationsfromsaid devices and which of said vibrations has the higher frequency.

7. Apparatus for comparing the speed of operation of two mechanicaldevices comprising two separate electric control means re.- sponsiveseverally to periodic vibrations produced by the operation of saiddevices, said control means acting respectively to vary the currents intwo electric circuits in accordance with the frequencies of saidperiodic vibrations, a rotary electro-magnetic indicating device havinga field winding and an armature winding, and means for connecting saidtwo electric circuits respectively to said armature and eld windings,whereby the speed of rotation of said indicating device gives anindication of the difference between the speedsofsaid two mechanicaldevices and the direction lof rotation of said indicating deviceindicateswhich of said mechanical devices is operating at the higherspeed.

8. Apparatus for comparing the operation ,of two watches comprisingseparate means responsive severally to the beats of the incassa variedrespeetivel by said microphones in accordance with t e frequencies ofthe beats -of said watches, two al" ion tube amplifiers having theirinput circ ts connected respectively to said two microphone circuits andmeans operated by the differential effect of the output currentsl ofsaid ampliers for showing which of the watches is running at the higherrate of speed and for indicating the diii'erence in speed of thewatches.

11. Apparatus for comparing the operation of two watches comprisingseparate means responsive severally to the beats of said watches, and anindicating instrument controlled by said separate means for indicatingwhich of the watches isoperating at the higher rate.

12. Apparatus for comparing the operation of two watches. comprisingseparate means responsive severally to the beats of said watches, saidmeans actingto vary two electric currents in accordance with thefrequencies of said beats, and an indicating de-A vice ]ointlycontrolled by said currents for the other when one or the other of saidwatches is operating at the higher speed.

. 15.v Apparatus for comparingthe operation of two watches comprisingtwo microphones each connected in a separate tuned circuit including asource of electric current, each of said microphones having means forengaging a watch and vibrating a resistance varying element inaccordance with the beats of the watch, whereby the currents-in the twotuned circuits are varied respectively in accordance with the speed atwhich the two watches are operated, andan indicating instrumentcontrolled by the saidcurrents for indicating the diiference in rate ofoperation of said watches and which of said watches is operating at thehigher rate.

16. Apparatus for comparmg the operation of two watches comprising twomicrol phones each connected in a separate-tuned circuit including asource of electric current,

each of said microphones having means for engaging a watch case andvibrating a resist-yv ance varying element 1n accordance with the Ybeats of the watch, whereby the currents in the two tuned circuits arevaried respectively in accordance with the speed at which the twowatches are operated, means for separately' amplifying said currents,and a rotary indicating instrument operated by said currents and actingto directly indicate the difference in rate of operation of saidwatches.

In testimony whereof I affix my signature.

ARTHUR P. DAVIS.

directly indicating which of said two watches is operating at thehighe-speed.

13. Apparatus for c'o paring the operation of two watches'comprisingseparate means responsive respectively to the beats of said watches, andacting to vary two eleC- tric currents in accordnace with thefrequencies of said beats, means for amplifying said currents and arotary device operated by the differential eiect of said currents forindicating, by its direction of rotation which of sid watches isoperating at the 'higher spee 14. Apparatus for comparing the operationof two watches comprising two microphones responsive respectively to thebeats` of the watches and acting to vary electric currents in accordancewith the frequencies of said beats, means for separately amplifying saidvarying currents, a rotary indicating device having a plurality of fieldwindfied currents being supplied to said field 'A windings and saidarmature winding respectively, andfinean's for producing a phasedisplacement between the currents in certain of said Veld windings,whereby said rotary device is caused to rotate in one direction orCERTIFICATE or coRREcTIoN.

Patent No'. 1,169,988. 1 Granted July s, 1930, im E ARTHUR Pl DAVIS.

` It ishereby certifiedl that error appears in tlIOe printedspecification ofthe above numbered patent requiring-correction asfollows: Page 1, strike out present line 69, insert instead the words"drawing,. in which"; page 4, line 89,

claim 6, for the misspelled Word 'separateqy" read separately; 'page 5,line 42, claim 13, for "respectively" read severally; line 43, for "and"read said mean; .fand line 44, for the misspelled word "accordnace" readaccordance; and that the `said Letters Patent should be read with thesecorrections therein that the san'Ie may conform to the lrecord of thecase in the Patent Office.' Signed and sealed this 9th day of September,A. D. 1930.

. M. J.I Moore, (Seal) Acting Commissioner of Patents.

